For more than six decades, these two rifle cartridges have dominated battlefields worldwide- but given their continued widespread use and numerous applications, can we objectively say one is better than the other?
Table of contents
Introduction
As we stated in the header, these are two of the most popular rifle cartridges on earth- both are used by tens of millions of soldiers, policeman, criminals, terrorists, militias and civilians alike, and can be found anywhere an armed conflict is raging- often facing each other directly.
Ever since their origins during the opening decades of the cold war, they have been compared countless times by countless people in numerous ways (including by military and state officials of both the Soviet Union and the United States), and while everyone has reached different conclusions on which is better, we will be comparing the two based largely on objective facts.
In this week's article, we will be comparing basic, quantifiable traits these two great cartridges have- their weight, speed, ballistic performance against human targets as well as barriers, accuracy, cost and reliability in the firearms they are most often chambered in.
Let's begin with their history...
History of the two cartridges
7.62x39
The world's most common assault rifle cartridge had its origins in the second world war, after the invasion of the Soviet Union by Nazi Germany in June, 1941.
During that conflict, the Soviet Army had encountered brutal, close-quarters urban combat where the long, cumbersome bolt-action Mosin-Nagant rifle that had been in service for over 50 years was beginning to show that it was ineffective for this new type of fast-paced, short range warfare and was so outdated it needed to be replaced.
The Soviets had had great success at combating the invading Wehrmacht with the semi-automatic SVT-40 series of rifles as well as with their submachine guns (namely the PPSh-41), but with world war 2 came the understanding that the submachine gun was underpowered for typical combat distances outside of these urban environments (which, according to studies by the U.S and German militaries, usually varied between 50 and 300 yards).
At the same time, the full-power "battle rifle" cartridges that where the mainstay of armies at the time where unnecessarily powerful for combat at these distances, as well as having excessive recoil and being too heavy to carry in large amounts, as would be expected of soldiers who would need to be constantly moving with the front. Additionally, they also made it harder for soldiers to concentrate enough to fire their weapons accuracy under the stress and noise of combat.
So, in 1943, the Soviet Union decided an "intermediate" cartridge- that is, a round that was light enough to carry in large amounts while also not being uncontrollable yet still able to put down enemy combatants- was needed and a meeting was held by the People's Commissariat of Armaments that July to brainstorm ideas.
Eventually, over 300 designs were drawn up, but discussions over the following months narrowed these options down considerably, until only 8 remained- these 8 designs where then tested, and a final product was drawn up in December of that same year. The cartridge was still undergoing active development, however, and production did not begin until March of the following year in 1944.
By the time it came to press this cartridge into widespread service in the latter half of the 1940's, the second world war had ended, but the need for an intermediate cartridge remained, especially as the prospect of another, even deadlier war with the United States and its allies seemed almost inevitable at the time.
With the introduction of the SKS rifle and, in 1949, the AK-47, the 7.62x39 cartridge went on to serve as the main rifle cartridge of the ground forces of not only the Soviet military, but also the militaries of most of its allies under the Warsaw pact as well as much of the developing world in general- it's success with both professional armies and irregular, untrained forces was immediate, and it remains as the most widespread assault rifle chambering to this very day.
5.56
The 5.56, like the 7.62x39, came about as a need to provide ground troops with more ammo and with a round that was appropriately suited for close-quarters combat- more powerful than a submachine gun, but without the heavy recoil and excessive weight of a full-power battle rifle cartridge, such as the .30-06 Springfield or the 7.62x51mm NATO, which it was designed to replace as the mainstay of American infantry.
Development on a new round for U.S troops begin in earnest in 1957, with the goal being to create a lightweight rifle that fired a light, fast projectile. The initiation of this new project was at the request of U.S Army officials and was worked on directly by several companies including Remington (from which the .223 Remington- the "civilian" version of the 5.56- would get its name).
By 1959, a design that could be agreed upon had been reached and was tested in the following years various times by numerous officials. Subsequently, the new cartridge was adopted by the U.S military in September of 1963.
The .223 Remington arrived just in time for the U.S entry into the Vietnam war and despite numerous early issues with the M16 rifle it was designed for, it soon won the respect of troops who, notably, where able to outgun enemy NVA soldiers and Viet Cong guerrillas armed largely with AK-47 type rifles (that fired 7.62x39 ammunition) almost every time.
It was also noticeably more lethal and accurate than its eastern opponent, as well as providing numerous other benefits (in fact, the U.S.S.R even developed a rough equivalent in the form of the 5.45x39 cartridge as a result of the .223 Reminton's success in the closing years of the war in order to address these shortcomings with the 7.62x39).
The .223 Remington remained the main service cartridge of the U.S military throughout the war and had impressed other members of the North Atlantic Treaty Organization (NATO) enough to standardize a round to replace the 7.62x51 in 1970. In October of 1980, the .223 Remington was selected and adopted by all NATO ground forces as the replacement after some slight tweaking by the Belgian firm FN Herstal, and this new, improved version was named the 5.56x45mm NATO- which still remains the main service rifle cartridge of most NATO forces to this day.
Direct comparisons
The two cartridges- despite being made to fulfill the same basic role- each have a pretty substantial list of differences between them in terms of performance and physical characteristics. For example, while the average 5.56 round weighs either 55 or 62 grains (3.56 to 4 grams), the 7.62x39 weighs approximately twice as much- usually about 122-124 grains (just under 8 grams). We'll explain why this is significant momentarily.
Below, we've created a simple table to summarize both the physical differences between the two as well their basic ballistic characteristics.
Note that this data is only for two specific loads- both are common full metal jacket (FMJ) rounds. The energy, muzzle velocity and other characteristics of a round are all be affected by the specific load as well as factors like bullet design, weight, length, material in construction etc. This means the table below is only generally representative of what you could expect from common 5.56 and 7.62x39 loads.
Cartridge | 5.56 (M855 out of a 20 inch barrel) | 7.62x39 (Wolf 124 grain bullet out of a 16 inch barrel) |
Bullet weight | 62 grains | 124 grains |
Average velocity (feet per second) | 3,100 | 2,320 |
Average muzzle energy (foot-pounds) | ~1,320 | ~1,450 |
Effective range (yards) | 500-600 | 300-400 |
Velocity at 100 yards | ~2,630 fps | ~2,000 fps |
Velocity at 200 yards | ~2,220 fps | ~1,710 fps |
Velocity at 300 yards | ~1,830 fps | ~1,460 fps |
Velocity at 400 yards | ~1,500 fps | ~1,250 fps |
Velocity at 500 yards | ~1,230 fps | ~1,100 fps |
Energy at 100 yards | ~950 ft-ibs | ~1,070 ft-ibs |
Energy at 200 yards | ~670 ft-ibs | ~800 ft-ibs |
Energy at 300 yards | ~460 ft-ibs | ~580 ft-ibs |
Energy at 400 yards | ~300 ft-ibs | ~430 ft-ibs |
Energy at 500 yards | ~200 ft-ibs | ~330 ft-ibs |
So, what does this all mean?
Well, for starters, we can see that an "average" 5.56 bullet, while weaker than many 7.62x39 rounds, still packs an effective punch out to a fair distance, and crucially- it remains supersonic out to a farther distance than the 7.62x39. This is important for anyone shooting long range, as a bullet dropping from a supersonic to subsonic velocity will become unstable in flight, tremendously lowering accuracy- note that the speed of sound at sea level at a temperature of 59 degrees Fahrenheit (15 degrees Celsius) is about 1,115 feet per second (about 340 meters per second).
Because of this, an extremely important characteristic difference between the two is the distance over which they can reasonably be expected to strike a man-sized target- while both the 7.62x39 and 5.56 rounds can readily hit targets out to at least few hundred meters in pretty much any weather condition you can reasonably encounter, the 5.56 almost always can reach out farther because it's lighter and faster than its Russian opponent.
Due to significant (and usually rapidly changing) variables in bullet drop being caused by air density, temperature and air pressure, we didn't display a trajectory chart for these two rounds, but because the 7.62x39 bullet is not only significantly slower, but is also about twice the weight of the 5.56 round, simple physics says the 7.62x39 will drop MUCH faster regardless of load used and regardless of any external atmospheric variables- even the lightest 7.62x39 bullets are still slower and much heavier than the very heaviest 5.56 loads (which can get up to 90 grains or more in weight). Most also reach transonic velocity about 100-200 yards before the 5.56 does.
On the note of bullet weight and speed, since energy equals mass times acceleration, we can also make the determination (confirmed by the real-world experience of the author- and probably anyone else who has shot both) that the heavy 7.62x39 round will kick harder than the 5.56 round even at its reduced velocity when compared.
So basically, if you want to shoot farther and/or more accurately, the 5.56 is the clear winner by a substantial margin due to its light, speedy ballistics.
But how do these rounds actually perform where it counts most- against their targets?
Here is where it becomes more opinion than fact, but even here, we can measure objective differences between the two.
Let's start with basic wounding capacity- without getting too deep into the physics behind it, there are generally two measures of how effective a bullet is against soft targets- the amount of energy it transfers to a target, and the size of the wound cavities (both from the temporary stretching of internal organs upon impact and permanent wound channel left behind by the bullet itself). Factors such as a bullet tumbling or bullet fragmentation are also often taken into account and can further increase the size of the wounds as well as impart even more energy into the target's vital organs.
As we previously said, in terms of energy alone, the 7.62x39 will come out on top in the vast majority of cases. However, this doesn't mean it's more lethal by default- in fact, one of the biggest shortcomings of early 7.62x39 rounds was the fact they punched right through human bodies and imparted little energy into their targets, and thus left relatively small wound cavities that were unlikely to be fatal unless something vital was struck- which was a lot to ask from the relatively inaccurate AK-47 rifle it was most commonly used with save for encounters at very close range.
This problem has been largely corrected by modern ammunition manufactures, however- many modern 7.62x39 rounds can and do tumble on impact and their effectiveness on human targets is noticeably increased as a result. Expanding 7.62 bullets and even some that can fragment and produce even more severe wounds exist as well- but even so, they still haven't quite earned the reputation for wounding that the 5.56 has.
On the other side of the aisle, the 5.56 round is notorious for being incredibly destructive to a human body- particularly when pushed to a high enough speed (usually around 3,000 feet per second or more). Early 55 grain rounds were especially devastating to human targets- bullets would not only rapidly tumble, but they'd fragment into pieces and damage organs even outside the wound cavity due to their extreme velocity. In fact, their effects where so violent some even considered the M16 rifle its virtually identical predecessor- the .223 Remington- was designed for to be an inhumane weapon.
Modern 5.56 ammo is even more effective- even rounds that do not travel fast enough or are designed to not fragment still often tumble and tear through flesh at a faster rate than 7.62x39 rounds, leaving messy wounds and shredded flesh behind them. Note however that 5.56 is largely dependent on velocity in order to maximize wounding potential, while the 7.62x39 is not.
More important than any of these, however, is the ability of the shooter to put rounds in a spot that puts the threat down- which is altogether hard to do under the stress of an armed encounter, but still almost certainly easier to do with the soft recoil of the 5.56 than the chunky kick of the 7.62x39.
Other points of consideration here include penetration (which I personally think they both excel at when needed, but the 5.56 is supposedly better for penetrating things like steel and body armor due to its much higher velocity), weight (you can carry two 5.56 rounds for every 7.62x39 round) and cost (the 7.62x39 is almost universally cheaper than the 5.56 regardless of the load you buy).
We'd also like to point out that the variety of 5.56 ammo is significantly greater than 7.62x39 ammo- meaning you're more likely to find a 5.56 round that suits your needs to a T than you are with 7.62x39 rounds.
Pros and cons of each
5.56 pros:
Faster, lighter projectile means it will travel farther and is usually more accurate (especially with match ammo)
Projectiles are (usually) more damaging to human tissue than 7.62x39
Recoils less than 7.62x39
Users can carry about twice as much 5.56 ammo compared to 7.62x39
There is a greater variety of 5.56 ammo available on the commercial market
5.56 cons:
The 5.56 depends greatly on velocity in order to cause effective wounds as well as penetrate barriers (although at shorter ranges it does this as good or better than 7.62x39)
5.56 lacks energy at longer ranges as well, but is nonetheless effective with good shot placement out to a few hundred yards
Is generally more expensive than 7.62x39
7.62x39 pros:
Has very high energy and retains energy over a longer distance than 5.56
Does not rely on velocity for terminal effectiveness (this is an important factor to consider when shooting out of a shorter barrel or at long distance)
Is most often significantly cheaper than 5.56
Has better barrier penetration beyond 100 yards or so compared to 5.56 (however, it does not perform as well as 5.56 against steel, body armor etc. due to its lower velocity)
7.62x39 cons:
Has significantly more recoil than 5.56
Wounding potential is more limited than 5.56 (but is still substantial and quite effective)
Has less range than 5.56
Conclusion and final thoughts
So... which is better?
Or more realistically, which do WE think is better?
Well, in a word... neither. They both do what they need and were designed to do just fine- to stop a person dead out to a few hundred yard and be reasonably accurate and cheap for issue to armies, policemen or anyone else who need to use a rifle.
To be clear, they each certainly have their strengths and weaknesses, and it's up to you to determine which one suits your needs the best.
For example, need a rifle that shoots flat and is accurate? Choose one chambered in 5.56. Do you prefer raw power and is distance and accuracy not a concern? 7.62x39 would probably suit you better. What one can do well, the other can do better, and both have relatively few shortcomings and weak points- except for long-range shooting (which they weren't really designed for, anyways).
But no matter what angle you approach it from, how you compare them, what your needs are or anything else, one cannot deny that these two inventions- which have helped build the modern world we know today- are two of the best rifle cartridges of all time and will probably remain the most widely used for many decades to come.
Until then- and likely beyond- the debate will continue to persist and will probably never be fully resolved.
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